1. Field of the Invention
The present invention relates to an improvement in a box-shaped facing-targets sputtering apparatus including a box-shaped facing-targets sputtering unit and a vacuum chamber, the sputtering unit including a rectangular parallelepiped frame having six faces, one of which serves as an opening face, and a pair of facing target units, each including a target and magnetic-field generation means formed of a permanent magnet which is provided so as to surround the target, which means generates a facing-mode magnetic field extending in a direction perpendicular to the surface of the target and a magnetron-mode magnetic field extending in a direction parallel to the target surface, in which the target units are provided on first opposing faces of the frame which are located adjacent to the opening face, and second opposing faces and the remaining one face of the frame are shutted, wherein the sputtering unit is provided on the vacuum chamber such that the opening face faces the vacuum chamber and a substrate on which a thin film is to be formed, the substrate being disposed in the vacuum chamber. The present invention also relates to a method for producing a compound thin film by use of the thus-improved sputtering apparatus.
2. Description of the Related Art
The aforementioned box-shaped facing-targets sputtering apparatus including the box-shaped facing-targets sputtering unit, which has been disclosed by the present inventor in Japanese Patent Application Laid-Open (kokai) No. 10-330936, is configured as described below.
As shown in FIG. 7, a box-shaped facing-targets sputtering unit 70 is configured such that facing target units 100a and 100b are mounted on opposing faces 71a and 71b of four faces 71a through 71d (among five faces 71a through 71e) which are provided adjacent to an opening face 71f, which serves as an opening of a rectangular parallelepiped frame 71, and such that the three faces 71c through 71e are covered by closure plates 72c through 72e, respectively. The target unit 100a includes a target 110a and magnetic-field generation means formed of a permanent magnet which is provided so as to surround the target 110a, and the target unit 100b includes a target 110b (not illustrated) and magnetic-field generation means formed of a permanent magnet which is provided so as to surround the target 110b. The entirety of the sputtering unit 70 assumes a rectangular parallelepiped box shape, which may be cubic. The box-shaped facing-targets sputtering apparatus has a configuration as described below. Specifically, as shown in FIG. 1, the box-shaped facing-targets sputtering unit is connected to a vacuum chamber such that the opening face 71f of the sputtering unit faces the vacuum chamber, and a substrate on which a thin film is to be formed is placed within the vacuum chamber so as to face the opening face 71f. 
In the sputtering apparatus having the above-described configuration, a magnetic field for generating and confining sputtering plasma is formed as in the case of a conventional facing-targets sputtering apparatus disclosed in, for example, Japanese Patent Application Laid-Open (kokai) No. 10-8246. Specifically, within a space provided between the facing targets of the facing target units including magnetic-field generation means (the space is hereinafter called a “(plasma) confinement space”), a facing-mode magnetic field extending in the direction perpendicular to the targets is formed throughout the targets, and, in addition, a magnetron-mode magnetic field extending in the direction parallel to the surfaces of the targets is formed in the vicinity of the target surfaces so as to surround the peripheral edges of the targets. As a result, high-density plasma is generated over the entire surfaces of the targets.
Therefore, in the box-shaped facing-targets sputtering apparatus including the box-shaped facing-targets sputtering unit, in which the five faces other than the opening face are shielded, sputtered particles fly, via the opening face, to the highly evacuated vacuum chamber in which the substrate is placed, and are deposited onto the substrate, to thereby form a thin film.
The aforementioned conventional box-shaped facing-targets sputtering apparatus has a compact configuration, and enables formation of a thin film of high quality at low temperature. Therefore, the sputtering apparatus has been applied to formation of various films. For example, the sputtering apparatus has been applied to formation of electrodes of organic EL devices, which have recently become of interest and have been increasingly developed for commercialization, and various studies have been performed on application of the sputtering apparatus to formation of the electrodes.
Such an electrode must be formed on an organic layer. Therefore, the electrode must be formed so as not to cause any damage to the organic layer serving as an underlying layer. In addition, the electrode must be in the form of a thin film of high quality (e.g., a thin film of low resistance), and, in some cases, the electrode must be in the form of a thin film exhibiting excellent transparency. Meanwhile, in the case where a protective layer is formed on an organic layer, the protective layer must be formed so as not to cause any damage to the organic layer serving as an underlying layer, and the protective layer must be in the form of a thin film exhibiting excellent protective properties (e.g., damp-proof property) and transparency.
Similar to the above case, in the case of production of a high-performance film such as a transparent heat-insulating film, when a compound thin film (e.g., a metal oxide thin film or a metal nitride thin film) is formed on an underlying layer, a thin film of high quality exhibiting intended characteristics must be formed so as not to cause any damage to the underlying layer.
Therefore, instead of being formed by means of conventional vacuum deposition, such a thin film must be formed by means of sputtering, which can form a film of high density exhibiting excellent uniformity.